Asynchronous transfer mode (ATM)-based techniques frequently are used in data communication systems to provide for the reliability of circuit switching and the flexibility and efficiency of packet routing. ATM is particularly useful in digital subscriber line (xDSL)-based systems, such as asynchronous DSL (ADSL).
ATM provides for the transmission of fixed-sized cells which then may be grouped together into frames. Referring to FIG. 1, a conventional ATM cell 100 is illustrated. The ATM cell 100 typically is constructed of 53 bytes, five of which comprise the ATM header which contains information used for network management. Generally, the ATM header includes a generic flow control (GFC) field 102, one or more virtual path identifier (VPI) fields 104, 106, one or more virtual channel identifier (VCI) fields 108-114, a payload type indicator (PTI) field 116, a congestion loss priority (CLP) field 118 and a header error control (HEC) field 120. The remaining 48 bytes of the 53 byte ATM cell 100 typically are reserved for payload field 122.
While cell headers, frame headers, and superframe headers generally are necessary in ATM for proper network management, it will be appreciated that their use often limits the nominal data transfer rate over an ATM line. To illustrate, because only 48 bytes of the 53 byte ATM cell 100 represent payload data, conventional ATM has an efficiency of approximately 90.5% on a cell-by-cell basis. Improving the size of the payload compared to the size of the header would allow payload data to be transmitted at a greater bit rate. Accordingly, a process for improving the ratio of payload size to header size in ATM cells would be advantageous.